Organopolysiloxanes having silanol groups at both molecular terminals, expressed by the chemical formula below, are conventionally known: ##STR2## These compound are widely employed in many fields, for example, as a room temperature curable liquid silicone rubber.
Further, silanols expressed by the chemical formulae below are known as compounds having one silanol group in a molecule: EQU (CH.sub.3).sub.3 SiOH, and ##STR3## However, these silanols undergo a condensation through the mechanism (A) shown below and, as a result, high purity organopolysiloxanes may be obtained by distillation but only at a disadvantageously low yield: EQU .tbd.Si-OH+OH-.vertline..fwdarw..vertline.Si-O-Si.vertline.+H.sub.2 O (A).
On the other hand, an organopolysiloxane containing one silanol group at one molecular end, expressed as below, is of interest: ##STR4## This compound may be synthesized by the living polymerization of cyclic organopolysiloxanes with silanols, as shown by the formula below, which is described in, for example, European Patent Specification, EP-A-0508490. ##STR5##
However, a complicated process is required to prepare such a silanol terminated compound with a high precision by this method and it also requires a high degree of technology. In addition, the importance of compounds having one silanol group per molecule has recently been recognized, therefore the development of methods which enable one to prepare them easily at high purity and high yield is strongly in demand.